1. Field of the Invention
This invention relates to tools for drilling pipeline holes and, more particularly, to tools for simplifying the process of repairing drilling-pipes, in situ.
2. Prior Art
In the process of laying pipes and tubing for utility applications, for example, laying telephone cables and heating-gas pipes, it is necessary that horizontal pipe-line holes be drilled or bored in the earth. The process normally involves using a drill-pipe or tube at the leading end of which a bit is carried. The drill-pipe and the bit which it carries are rotated, either manually or by means of a motor, such as an air motor, while the drill-pipe is urged forward. Initially a trench or slot may be dug in the earth to give the hole the desired initial depth. Sometimes "spud" boring is used to reduce the length of the initial trench. "Spud" boring is slant drilling at a predetermined slope so as to arrive at the target area with the desired depth of the hole. In either case, as the drill-pipe is rotated and advanced it is subjected to a high torsional forces and significant shear stresses. Occasionally these shear stresses are large enough to break the drill-pipe which stops the drilling process until the location of the break is determined and the pipe is welded back into one piece.
The prior art procedure for fixing broken drill-pipe was both time consuming and difficult. In that procedure there were three steps in retrieving and re-attaching the broken pipe to the main drill-pipe: the installation crew has to (1) determine the location of the break, (2) excavate a large enough hole around the break to enable a welder to get in and work and then, (3) have the welder weld the pipe. The problem is not over at that time, because it is nearly impossible to perfectly align the two portions of a broken pipe, so a weak point is generated at the weld. As the job continues, it is somewhat common for the weld to break. Thus, the digging and welding process has to be repeated.
An investigation by these inventors over the last two years of dealing with this type of drill-pipe showed that it took approximately 17 extra hours to complete a job where a drill-pipe break occurred.
Therefore, it is a first object of this invention to overcome the problems of the prior art.
It is a further object of this invention to provide a device for quickly and easily overcoming the problem of re-joining, for actual and effective continued drilling, the several segments of a broken drill-pipe.